Hi. I don't if it is permitted to ask something here, I'm sorry. I have an iMac mid 2011 2.7 21.5 inch. Can I add 8GB RAM modules? It's supposed to allow a maximum of 16gb, but I've read that it could allow up to 32 GB. Is it true? Thanks

Yes, you can put in 8 GB modules maxing out the system at 32 GB. But before you load it up that far make sure the OS you are using is the latest and the apps you are using can leverage it. Even then you may want to first go to 16 GB using two modules to make sure what you are working on really needs this much. Second, while RAM is important, your HD (SSD) storage needs to be evaluated at the same time.

Remember its the matching of all of the components that makes a fast race car! Having a big engine that burns fuel faster means you need to turn into the pit stop more often to get refueled. So you need a bigger fuel tank. But the weight of the added fuel requires better shocks & tires and maybe even more framing. I hope you see were I'm going here. Its the whole system that needs to be balanced. Over doing one piece often won't help.

Thanks for your answer, Dan. So, the next step you recommend is to replace the HD by a SSD, am I right? What else would you recommend? I use heavy orchestral sample libraries for both composing music and scoring for film, that's why upgrading RAM was the first thing that came to my mind. Thanks again for your great answer and help.

So in your case you would use the HD as your bulk storage and use the new SSD as your boot, app & work area. You'll likely want as large a SSD as you can afford here as the composition(s) you are working on will need to fit on the SSD in addition to the other samplings you are working from.